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{{Featured Article Candidate
| article    = Proteus mirabilis
| supporters  = [[User:Milton Beychok|Milton Beychok]]
| specialists = [[User:Daniel Mietchen|Daniel Mietchen]]
| created    = 2009-05-12
| score      = 4
}}


{{Featured Article Candidate
{{Featured Article Candidate

Revision as of 15:02, 12 June 2009

The New Draft of the Week is a chance to highlight a recently created Citizendium article that has just started down the road of becoming a Citizendium masterpiece.
It is chosen each week by vote in a manner similar to that of its sister project, the Article of the Week.

Add New Nominees Here

To add a new nominee or vote for an existing nominee, click edit and follow the instructions


Table of Nominees
Nominated article Score Supporters Specialist supporters Date created
Developing Article Three Week Hero 2 Milton Beychok;
Meg Ireland 		2009-05-18

Transclusion of the above nominees (to be done by an Administrator)

View Current Transcluded Nominees (after they have been transcluded by an Administrator)

The next New Draft of the Week will be the article with the most votes at 1 AM UTC on Thursday, 18 June 2009. I did the honors this time. Milton Beychok 04:02, 11 June 2009 (UTC)

Text in this section is transcluded from the respective Citizendium entries and may change when these are edited.

Nominated article Supporters Specialist supporters Dates Score
Developing Article Wrench (tool): A fastening tool used to tighten or loosen threaded fasteners, with one end that makes firm contact with flat surfaces of the fastener, and the other end providing a means of applying force [e]

A wrench (American English), or spanner (British English), is a fastening tool used to manipulate threaded fasteners such as nuts, studs and bolts. They also may manipulate threaded structural elements such as pipes. The wrench is sized and shaped to put pressure and leverage on flat faces of the fastener, and then is moved in the direction of rotation needed to loosen or tighten the fastening assembly.

Hand tools

The most common hand wrenches are made either from a flat bar of steel, or from cylinders. Even with these two types, the wrench can either completely or partially surround the fastener.

Flat Bar

The most common hand wrenches either are open-ended, such that they have sides parallel to two or more facets of the nut, or box, which surrounds all sides of the nut. These types can drop over the nut no matter how much of the screw or bolt protrudes.

The longer the handle of the wrench, the more force can be applied to the fastener. One technique is to carry a length of pipe, which can slip over the wrench and act as a handle extender. Do be warned, however, that a sufficiently long pipe can exert enough force to break the wrench or the fastener.

Double-sided open-end wrench
Double-sided box-end wrench

Still, there are times when it is absolutely necessary to release a stuck fastener. It is usually wise first to apply a penetrating lubricant to the fastener, and tap it gently to let the lubricant reach the threads, waiting briefly before applying force. Yet another dangerous but sometimes necessary technique is to hit the handle of the wrench with a hammer; do remember to hit it in the direction in which the fastener needs to turn. Gloves and eye protection are wise precautions when hammering a wrench. An even more desperate expedient is to heat the fastener to expand it, which may destroy the hardness or toughness of the metal. Occasionally, it is possible to chill the piece to which the fastener is attached, contracting it and helping break the adhesion.

For some specialized applications, typically where only authorized persons are to adjust the fastener, the sides of the wrench head may not be parallel. For example, the nuts on fire hydrants are pentagonal, so they cannot be manipulated with a standard wrench shape.

Combination wrench

(CC) Photo: Derek Hodges
A combination wrench
A combination wrench has a one open and one box end, usually of the same size. The open end is more useful when there is limited access to the fastener. Box ends can get a better grip when the flats of the nut are deformed.

Adjustable open wrench

PD Image
Adjustable wrench

An adjustable wrench has one fixed jaw, and one that is adjustable by means of a screw adjustment, usually made in one piece with the adjustable jaw. In the U.S., this is often called a Crescent wrench after the first well-known manufacturer, while it is a Bahco wrench in Dutch usage, after the Swedish manufacturer. The obvious advantage of the adjustable wrench is that an entire set of wrenches need not be carried when the size of the fastener to be adjusted is not known. The disadvantage is that the adjustment can slip, and generally cannot apply as much force as a solid wrench.

It should be mentioned, if mostly to condemn the practice, that pliers are sometimes used to adjust nuts. Most types of pliers, however, do not have parallel jaws, but angled ones. These are apt to deform a nut if heavy pressure is applied.

Pipe wrench

Pipe wrench

Pipe wrenches grasp threaded pipes and turn them, so they do not have flat jaws. One common type has curved jaws, with the wrench designed to slip slightly so it can be repositioned as the pipe moves under it. These were called Stillson wrenches after the inventor; they are sometimes, incorrectly, called monkey wrenches.

Another type does not have jaws, but instead a chain that tensions against the pipe.

Some plumbing fixtures have a nut-like shape molded into the metal, so that a flat-jawed wrench can be used. This is the application intended for the increasingly rare monkey wrench.

Socket wrenches and nutdrivers

Sockets proper are single pieces of cast or machined metal, with one end shaped to slip over the fastener to be manipulated, and the other to receive a driveshaft to turn it. The shaft end may actually have a depression, or even a spring-loaded bearing, to help lock the shaft into place. In combination, the driveshaft and socket are extremely strong in rotation, but should separate easily with linear traction.

Where the English measurement system is used, the shaft diameter is most often 3/8" or 1/4" for general purposes. 1/2", 3/4", and 1" drives are used for heavy equipment. Both metric and English system sockets, however, can snap onto the male end of the shaft.

Adapters are available to convert between shaft sizes. For example, one might have a large nut but only a 1/4" shaft system, so an adapter can allow a 3/8" socket to be used with that shaft.

Basic handle and extension

The most basic driver is a shaft with a handle, much like a screwdriver, but with a socket-mating connector rather than a screwdriver bit. Another very common variant, called an extension, has a male connector that mates with the socket at one end, and a female connector that accepts another socket tool at the other. Multiple extensions can be snapped together for extra length.

Nutdrivers

Nutdrivers are a permanently attached set of socket, driveshaft, and handle. Some nutdrivers have hollow shafts, so bolt length protruding above the nut goes into the hollow and does not interfere with rotation.

Aids to leverage

Most often, however, at the end of the extension away from the socket, a tool to improve the leverage of driving is attached. One such tool is a ratchet, which, at first, looks like an open-ended or box wrench. The male connector, however, is attached to a disk and mechanical components inside the ratchet head. There is a small control that selects the direction (i.e., loosening or tightening) in which the socket is to be moved. Once that control is set, the ratchet moves freely in the other direction, so it can be repositioned easily; it is not necessary to have 360 degree access above the fastener -- just enough working space to move the ratchet handle.

Other ways to improve leverage include various pivoting handles. One type looks like the brace (tool) used to drive hand drills; there is a socket fitting rather than a chuck at the working end. The operator holds a knob, fitted with bearings in which the shaft turns, and cranks a handle.

Another type, called a flex handle, is related to the rachet, but, rather than rotating, the handle pivots 180 degrees so it can be repositioned quickly. A flex handle is simpler, cheaper, and may be able to apply more force than a rachet.

Torque wrenches

A torque wrench is both a fastening tool and a measuring device. It is used where precise measurement of the tightness of a bolt is necessary.

It has been suggested that a quantum mechanical torque wrench can measure either the torque, or find the bolt, but not both.

Spanners (precision)

While a spanner is a general term in British English for "wrench", there is a specialized tool always known as a spanner. It consists of a bar with two or more protruding pins, sometimes adjustable in distance, that fit into corresponding holes in a fastener an allow it to be turned. The bar is connected to a shaft or other mechanism to allow turning, or sometimes the spanner is built not as a bar, but as a pliers-like device with the pins at the work end. Spanners are often used in optical work, on the retaining rings of lens elements.

Power wrenches

Impact wrenches

One of the most common types is a power-operated driver for sockets, the sockets usually made of extra-strong metal. Pneumatically driven impact wrenches are extremely common in the automotive industry; air drive does not generate the sparks that an electric motor could produce, which would be hazardous in the presence of petroleum products.

For other applications, however, electric impact wrenches are increasingly common, especially cordless battery-powered wrenches with great portability. For some heavy applications, the impact energy may be provided by an explosive cartridge.

There are impact wrenches that are hand-powered, but by hitting a specific part with a hammer, allowing great force to be applied.

Power torque wrench

Intended for industrial applications, these are often powered hydraulically, which allows great precision. (Read more...)

Howard C. Berkowitz 3


Developing Article Three Week Hero: A 1969 album recorded by P. J. Proby, which featured all four future members of Led Zeppelin. [e]
This article may be deleted soon.
To oppose or discuss a nomination, please go to CZ:Proposed for deletion and follow the instructions.

For the monthly nomination lists, see Category:Articles for deletion.


Three Week Hero
Image:TWHalbum1969.jpg
Type Studio album
Artist P. J. Proby
Release Date 8 April 1969
Recorded September 1968 at Olympic Studios, London.
Genre Rock, blues rock, pop
Language English
Length 39 min 26 secv
Label Liberty Records
Catalogue LBS 83219 (US), LBL 83219 (UK)
Producer Steve Rowland
Engineer Mike Weighell & John Macswith

Three Week Hero is an album released by rock singer P. J. Proby on 8 April 1969, by Liberty Records. The album contains a mixture of dramatic pop, blues, Rock music|rock, and country style songs, a departure from Proby's trademark pop sound of the 1960s. While it did not succeed commercially, it is best remembered today as the first time all four members of Led Zeppelin recorded together in the studio, which revived interest in the recording.[1] Proby recollects:

‘ Come the last day we found we had some studio time, so I just asked the band to play while I just came up with the words. ... They weren't Led Zeppelin at the time, they were the New Yardbirds and they were going to be my band.[2] ’

Jimmy Page had previously sessioned for Proby on his biggest success 'Hold Me', which reached number 3 in the UK charts. Other sessions soon followed for 'Zing! Went the Strings of My Heart', 'Stagger Lee', 'Linda Lu', 'Rockin' Pneumonia and the Boogie Woogie Flu', and 'Hanging from Your Love Tree'. Due to poor managerial and investment advice, Texan-born Proby was declared a bankrupt in the United States of America|United States in 1967, and decided to try his luck in the United Kingdom by relocating there in 1968. Members of Led Zeppelin were invited to participate after John Paul Jones had already pre-booked the session as a commitment prior to August 1968.[3] The medley 'Jim's Blues'/'George Wallace Is Rollin' In This Morninˈ', features all four members with Robert Plant playing harmonica and tambourine. 'Today I Killed a Man' reached number 13 on the Dutch singles chart,[4] an American Civil War song ostensibly redirected towards the Vietnam War. Many of the ideas behind these songs would be revisited on the Family Dogg's 1969 album A Way of Life, whose members appeared as backing singers, and this release was also produced by Steve Rowland. The song 'Sugar Mama (Led Zeppelin song)|Sugar Mama' recorded by Led Zeppelin at Morgan Studios in 1969, is not the same 'Sugar Mama' recorded on this album. The album was reissued on compact disc in October 1993.

Album information

Track listing:

  • Side 1:
  1. 'Three Week Hero' (John Stewart) – 2:56
  2. 'The Day That Lorraine Came Down' (Young) – 3:14
  3. 'Little Friend' (Robin Gair, Peter Mason) – 4:01
  4. 'Empty Bottles' (Albert Hammond, Mike Hazlewood) – 2:53
  5. 'Reflections (of Your Face)' (Amory Kane) - 5:14
  6. 'Won't Be Long' (J Leslie McFarland) - 3:41
  • Side 2:
  1. 'Sugar Mama' (Woodley, Young) – 2:50
  2. 'I Have a Dream' (Terry Hansley, Alec Wilder) – 4:45
  3. 'It's Too Good to Last' (Baker, Stephens) – 3:14
  4. 'New Directions' (Albert Hammond, Mike Hazlewood) – 3:46
  5. 'Today I Killed a Man' (Roger Cooke, Roger Greenway) - 3:24
  6. Medley: 'It's So Hard to Be a Nigger'/'Jim's Blues'/'George Wallace is Rollin' in This Morninˈ' (Hillery, traditional) – 7:38

Chart history

Album

Chart (1969) Peak position
US Billboard The 200 Albums Chart -

Singles

Year Single Chart Position
1969 'Today I Killed a Man' US Billboard Hot 100 Singles Chart (Pop Singles) -
Personnel
  • Musicians:
    • P. J. Proby - vocals
    • Jimmy Page – acoustic, electric, and pedal steel guitar
    • Robert Plant – harmonica, tambourine, backing vocals
    • John Paul Jones – bass guitar, piano, organ, arranger
    • John Bonham - drums, conga, percussion
    • Amory Kane - acoustic guitar, strings
    • Alan Parker - electric guitar
    • Alan Hawkshaw - piano, organ
    • Clem Cattini - drums
    • Stan Barrett - percussion
    • Dennis Lopez - percussion
    • The Jericho (The Family Dogg with Bob Henry) - backing vocals ("Won't Be Long" and "I Have a Dream")
  • Production:
    • Steve Rowland – producer, arranger ("It's So Hard ..." medley)
    • Reg Tilsley - arranger ("Reflections (of Your Face)")
    • Mike Weighell - engineer (Lansdowne studio)
    • John Macswith - engineer (Lansdowne studio)
    • Spencer Leigh - liner notes
    • Gustav Karl Moody - art direction, cover design
    • Anthony Lloyd Parker - photography
    • Steve Thomas - art direction

Notes

  1. ↑ Ian Fortnam, 'Dazed & confused', Classic Rock (magazine)|Classic Rock: Classic Rock Presents Led Zeppelin, 2008, p. 43.
  2. ↑ Fred Dollar (2005). Led Zep were my backing band, 83. 
  3. ↑ Welch, Chris (2002). Peter Grant: The Man Who Led Zeppelin, 62. ISBN 0-7119-9195-2. 
  4. ↑ Top 100 Singles - 27 December 1969. dutchcharts.nl. Retrieved on 2009-04-20.
 (Read more...) 		Milton Beychok;
Meg Ireland 		2


Current Winner (to be selected and implemented by an Administrator

To change, click edit and follow the instructions, or see documentation at {{Featured Article}}.

(PD) Image: Milton Beychok
Schematic diagram of a steam generator in a conventional coal-fired power plant.

An air preheater (APH) is a general term to describe any device designed to preheat the combustion air used in a fuel-burning furnace for the purpose of increasing the thermal efficiency of the furnace.

In particular, this article describes the combustion air preheaters for the large fuel-burning furnaces used to generate steam in thermal power plants. The air preheater increases the steam generator's thermal efficiency by preheating the combustion air with heat recovered from the hot combustion flue gases (see the adjacent diagram).

Types

The two most often used categories of air preheaters in thermal power plants are regenerative air preheaters and tubular air preheaters.[1][2][3][4]

Regenerative air preheaters

The two most common types of regenerative air preheaters are

  • The rotating-plate regenerative air preheater, often referred to as a RAPH. The RAPH was invented by Fredrik Ljungström, who was a Swedish engineer, and is also called a Ljungström air preheater.
  • The stationary-plate regenerative air preheater, often referred to as a Rothemuhle because Rothemühle is the German town where the original manufacturer produced them for many years.

Regenerative air preheaters may also be categorized as recuperators, which are special types of heat exchangers designed to recover or reclaim heat in order to reuse or recycle it.

Rotating-plate regenerative air preheater

(PD) Image: U.S. Environmental Protection Agency
A typical rotating-plate regenerative air preheater.[2]
The rotating-plate air preheater (RAPH) consists of a central rotating-plate element installed within a casing that is divided into sectors. There are three basic designs for the rotating-plate element:[5][6]
(PD) Image: U.S. Environmental Protection Agency
A typical rotating-plate regenerative air preheater.[2]
  • The bi-sector design has two sectors.
  • The tri-sector design has three sectors.
  • The quad-sector design has four sectors.

In the tri-sector design, the steam generator's hot flue gas flows through the largest sector (usually spanning about half the cross-section of the casing) and transfers some of its heat into the heat-absorbing material within the rotating wheel element. The cooled flue gas is then routed to further treatment in dust removal and other equipment before being vented from the flue gas stack. Ambient air is blown through the second, smaller sector by a centrifugal fan and absorbs heat from the heated material as it rotates through that smaller sector. The heated air then flows into the steam generating furnace as combustion air. The third sector is the smallest one and it heats a portion of the ambient air which is then routed into the coal pulverizations and is used to transport the coal-air mixture to coal burners. Thus, the total air heated in the RAPH provides: heated primary combustion air, heated air to remove moisture from the pulverized coal and carrier air for transporting the pulverized coal to the coal burners. Since the flue gas pressure is lower than the pressure of the air being heated, there is some small leakage (between the sectors) of flue gas into the air.

The bi-sector design is used in thermal power plants burning fuels (such as oil or gas) that do not require pulverizing or removal of moisture and therefore have need for heated air other than for combustion air.

The quad-sector design has a large sector heated by flue gas and three air-heating sectors: one is for the combustion air and that sector is flanked by two smaller air sectors. In applications such as circulating fluid bed (CFB) combustion systems where the differential between the air pressure and the flue gas pressure is even higher than in a conventional coal-fired steam generator, flue gas pressure, such a design is ideal since it acts to reduce the leakage of air into the flue gas.[6]

The rotating wheel element rotates quite slowly (around 3-5 revolutions per minute) to allow optimum heat transfer first from the hot exhaust gases to the element and then, as it rotates, from the element to the air in the other sectors.

Construction features

The heat-absorbing material in the rotating wheel element consists of vertical corrugated plates pressed into steel baskets, with sufficient space between the plates for the flue gas to pass through. The plates are corrugated to provide more surface area for the heat to be absorbed and also to provide needed rigidity. The baskets are designed to be replaceable as needed.

The vertical shaft that rotates the wheel is supported on thrust bearings at the lower end lubricated with an oil bath that is cooled by water circulating in coils inside the oil bath. Cooling of the bottom end of the shaft is needed since that is where the hot flue gas enters the preheater. The top end of the shaft has a simple roller bearing to hold the shaft in a vertical position.

Radial supports and cages for holding the corrugated plate baskets in position are attached to the rotating shaft. Radial and circumferential seal plates are also provided to minimize leakage of flue gas or air between the sectors.

For cleaning of the baskets while in operation, steam jets are provided to blow any fly ash (deposited by the flue gas) into an ash hopper below the preheater.

The rotating shaft is driven by a motor and gearing. To avoid uneven thermal expansion and contraction resulting in damage to the rotating wheel, the rotation must be started before starting the steam generator and must also be kept in rotation for some time after the steam generator is shut down.

The baskets of corrugated plates are subject to abrasive and corrosive wear from the fly ash and corrosive gases in the flue gas. Hence frequent replacements are required and new baskets are always kept on hand and ready for use.

Stationary-plate regenerative air preheater

(PD) Image: Milton Beychok
A typical stationary-plate regenerative air preheater.

The heat absorbing element in this type of regenerative air preheater is stationary rather than rotating. Instead, the air ducts in the preheater are rotated so as to alternately expose sections of the heating absorbing element to the upflowing air.

The hot flue gas enters at the top of the preheater and flows down through those exposed sections of the stationary heat-absorbing element that are not blocked by the rotating air outlet ducts, thus heating those sections of the stationary element. As the air ducts slowly rotate around, they pass over the heated sections and the incoming air is heated as it flows upward through those heated sections.

As indicated in the adjacent drawing, there are rotating inlet air ducts (inside the outer casing) at the bottom of the stationary heat absorbing element as well as the rotating outlet air ducts at the top of the stationary element.

The basic heat transfer principals of the stationary-plate regenerative preheater are the same as for the rotating-plate regenerative preheater. The table below provides a comparison of some design parameters between the rotating-plate and stationary-plate preheaters:

Some Comparisons Between Rotating-plate
and Stationary-plate Regenerative Air Preheaters[7]
  Rotating-plate Stationary-plate
Revolutions per minute 1.5 – 4.0 (a) 0.7 – 1.4 (b)
Gas flow area, % of total 40 – 50 50 – 60
Air flow area, % of total 35 – 45 35 – 45
Seal section area, % of total 8 – 17 5 – 10
(a) Revolutions per minute of the rotating plate element
(b) Revolutions per minute of the rotating air ducts

Tubular type

(PD) Image: Milton Beychok
A typical tubular air preheater[8]

Tubular air preheaters may have a number of configurations:[2][8][9]

  1. A bundle of vertical tubes through which the flue gas flows downward (see adjacent diagram) and exchanges heat with ambient air flowing horizontally across the exterior of the tubes. Baffles are usually provided so that the air flows across the tubes a number of times. For example, as shown in the adjacent diagram, the air flow across the tubes three times and is referred to as 3-pass tubular air preheater.
  2. The same as (1) above except that the flue gas flows upward rather than downward.
  3. A bundle of horizontal tubes through which the air flows and exchanges heat with the hot flue gas flowing downward across the tube bundle. In some designs, there may be three separate horizontal tube bundles one above the other. The air enters the lower tube bundle from the right-hand side, exits on the left-hand side and then enters the middle tube bundle on the left-hand side and exits on the right-hand side. Finally, the air enters the upper tube bundle on the right-hand side and exits on the left-hand side. In essence, such a design is similar to the 3-pass design of (1) above except that the air is in the tubes rather than outside the tubes.

A number of new circulating fluid bed (CFB) and bubbling fluid bed (BFB) steam generators are using tubular air preheaters, which avoids the air leakage associated with regenerative air preheaters.

Dew point corrosion

The water dew point of air or any other gas containing water vapor usually refers to the temperature (for a given pressure) at which the air or gas is saturated with water vapor. That means that the air or gas is at the point where the water vapor will start to condense into liquid water if the temperature is lowered beyond that point.

As a broad generality, the combustion flue gases from steam generators fueled by coal, fuel oil, natural gas, or biomass are composed of carbon dioxide (CO2) and water vapor (H2O) as well as nitrogen and excess oxygen remaining from the intake combustion air. Typically, more than two-thirds of the flue gas is nitrogen. The combustion flue gases may also contain small percentages of air pollutants such as particulate matter, carbon monoxide, nitrogen oxides, and sulfur oxides in the form of gaseous sulfur dioxide (SO2) and gaseous sulfur trioxide (SO3). The SO3 is present because a portion of the SO2 formed in the combustion of the sulfur compounds in the steam generator's furnace fuel is further oxidized to SO3 as the flue gas travels through the superheater and reheater sections of the steam generator (see the above diagram of a steam generator). The gas phase SO3 then combines the vapor phase H2O to form gas phase sulfuric acid H2SO4:[10]

H2O + SO3 → H2SO4

Because of the presence of gaseous sulfuric acid, the dew point of most flue gases is much higher than the water dew point of air and the flue gas dew point is referred to as the acid dew point. That is the flue gas temperature at which acid will begin to condense out of the flue gas if the temperature is lowered beyond that point. For example, a flue gas with 5 volume % water vapor and containing no acid gases has a water dew point of about 32 °C (90 °F). The same flue gas with the addition of only 0.01 volume percent of SO3 will have an acid dew point of about 118 °C (244 °F).[11]

The acid dew point of a combustion flue gas depends upon the composition of the specific fuel being burned and the resultant composition of the flue gas. Given a flue gas composition, its acid dew point can be predicted fairly closely. As an approximation, the acid dew points of flue gases from thermal power plants range from about 120 °C to about 150 °C (250 to 300 °F).

All of the air preheater types incur erosion problems to some extent from the fly ash particles in the flue gas. If the hot flue gas temperature in an air preheater is lowered to below its acid dew point, then the air preheater also incurs corrosion problems which can be quite severe. That is especially true of the tubular air preheaters. For that reason, many air preheaters have a means for the air to partially bypass the air preheater (see above tubular air preheater diagram) so that the amount of heat exchange can be controlled to avoid lowering the flue gas temperature below the acid dew point.

To mitigate dew point corrosion, the tubular air preheaters may use ceramic or Teflon-coated tubes and the regenerative air preheaters may use special corrosion-resistant steels or enameled materials.

The addition of limestone (CaCO3) into circulating fluidized bed (CFB) steam generators results in capturing 95% or more of the gaseous SO2 in the combustion product gases as solid calcium sulfate (Ca2SO4) and that occurs before the SO2 has time to be further oxidized to SO3. Thus, the acid dew point of the flue gas from a CFB steam generator is higher than from conventional thermal power plant steam generators. That means that the air preheaters in CFB units have considerably less dew point corrosion problems. That may also be one of the reasons why a number of the newer CFB units are using tubular preheaters.

References

  1. ↑ Sadik Kakaç and Hongtan Liu (2002). Heat Exchangers: Selection, Rating and Thermal Design, 2nd Edition. CRC Press. ISBN 0-8493-0902-6. 
  2. ↑ 2.0 2.1 2.2 2.3 Course SI:428A Online publication of the U.S. Environmental Protection Agency‎'s Air Pollution Training Institute, known as APTI (Scroll down to page 23 of 28)
  3. ↑ Sadik Kakaç (Editor) (April, 1991). Boilers. Evaporators and Condensers. Wiley Interscience. ISBN 0-471-62170-6.  (See Chapter 8 by Z.H. Lin)
  4. ↑ Lawrence Drbak, Patricia Boston, Kalya Westra, and R. Bruce Erickson (Editors) (1996). Power Plant Engineering (Black and Veatch). Chapman & Hall. ISBN 0-412-06401-4. 
  5. ↑ The Ljungström® Air Preheater
  6. ↑ 6.0 6.1 Ljungström® Air Preheater Arrangements
  7. ↑ Prabir Basu, Kefa Cen and Louis Jestin (1999). Boilers and Burners: Design and Theory, 1st Edition. Springer. ISBN 0-387-98703-7. 
  8. ↑ 8.0 8.1 http://www.egcfe.ewg.apec.org/Documents/Costs&EffectivenessofUpgradingOlderCoal-FiredPowerPlantsFina.pdf Costs and effectiveness of upgrading and refurbishing older coal-fired power plants in developing APEC economies] Asia-Pacific Economic Cooperation (APEC) Energy Working Group, Expert Group on Clean Fossil Energy, June 2005
  9. ↑ Performance Analysis of Primary Air Heater Under Particulate Condition in Lignite-Fired Power Plant Journal of Engineering, Computing and Architecture, Vol. 1, Issue 2, 2007
  10. ↑ Predicting Sulfuric Acid Emissions from Power Plants]
  11. ↑ Burning Sulfur Compounds A publication of the Banks Engineering Company of Oklahoma.
(Read more...)

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Ranking

  • The list of articles is sorted by number of votes first, then alphabetically.
  • Admins should make sure that the votes are correctly tallied, but anyone may do this. Note that "Specialist Votes" are worth 3 points.

Updating

  • Each Thursday, one of the admins listed below should move the winning article to the Current Winner section of this page, announce the winner on Citizendium-L and update the "previous winning drafts" section accordingly.
  • The winning article will be the article at the top of the list (ie the one with the most votes).
  • In the event of two or more having the same number of votes :
    • The article with the most specialist supporters is used. Should this fail to produce a winner, the article appearing first by English alphabetical order is used.
    • The remaining winning articles are guaranteed this position in the following weeks, again in alphabetical order. No further voting should take place on these, which remain at the top of the table with notices to that effect. Further nominations and voting take place to determine future winning articles for the following weeks.
    • Winning articles may be named New Draft of the Week beyond their last eligible date if their circumstances are so described above.

Administrators

The Administrators of this program are the same as the admins for CZ:Article of the Week.

References

See Also


Citizendium Initiatives
Eduzendium | Featured Article | Recruitment | Subpages | Core Articles | Uncategorized pages |
Requested Articles | Feedback Requests | Wanted Articles
 
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